Abstract 4362699: Association of Gillmore score with presence and development of atrial fibrillation at 1 year in a large, real-world cohort of patients with transthyretin amyloid cardiomyopathy

Introduction: Transthyretin amyloid cardiomyopathy (ATTR-CM) is a disease of misfolded transthyretin deposition into cardiac structures, very commonly causing arrythmias. Reports from older amyloid populations have shown that atrial fibrillation (AF) prevalence is higher at higher Gilmore stages. Given that, nowadays, ATTR-CM is being diagnosed at an earlier stage, we sought to reevaluate the association between Gillmore score and prevalence of AF at time of diagnosis and development of AF at one year. Research Question: In a large, real-world and recent cohort of patients with ATTR-CM, what is the interaction between a higher Gillmore stage of ATTR-CM and AF? Methods: Patient data was obtained from a prospective registry of ATTR-CM patients at our institution from 2015-2024. Patients were excluded from the cohort if they did not have NT-proBNP or eGFR data available within 6 months of ATTR-CM diagnosis. Primary analysis was 1 year outcome of AF or death. Results: Of the 1380 patients with ATTR-CM, only 1215 patients had NT-ProBNP and eGFR data to be included in the analysis. Of the 1215, 745 (61.3%) had a prior diagnosis of AF at the time of ATTR-CM diagnosis. Most patients (637, 52%) were in Gillmore Stage 1 at ATTR diagnosis. The prevalence of AF at the time of ATTR diagnosis was increasingly higher at higher Gillmore stages (Stage 1: 332/637, 52%; Stage 2: 266/392, 68%; Stage 3: 147/186, 79%). Of the patients alive at 1-year, new AF was present in 9% (28/302) of patients in Gilmore Stage 1, 19% (24/121) in Stage 2, and 17% (5/29) in Stage 3 (Figure 1). The combined outcome of AF and death at 1 year of those who did not have AF at baseline was highest with Gilmore stage 3 (38%) compared to Gilmore Stage 1 (10%) or Stage 2 (23%). Conclusion: In our recent cohort of patients, a progressively higher Gillmore score was associated with both a higher prevalence of AF at the time of ATTR-CM diagnosis and development of AF at 1 year after ATTR-CM diagnosis. Death at 1 year following ATTR-CM diagnosis increases exponentially for those at Gilmore stage 3. This study highlights that despite diagnosing ATTR-CM earlier, AF is still highly prevalent even in early stages of the disease and highlights the importance of continued surveillance for the development of AF in ATTR-CM.